Doxycycline and Tetracycline Interaction
Drug interaction information between Doxycycline and Tetracycline.
Doxycycline and Tetracycline have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Doxycycline and Tetracycline. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Both of these medicines belong to the same family of antibiotics, which can increase the risk of side effects without helping you get better faster.
FDA Label Information
Drug Interactions Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage. Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines in conjunction with penicillin. Absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, and iron-containing preparations.
Doxycycline Also Interacts With
- Rifampin moderate
- Carbamazepine minor
- Bismuth Subsalicylate minor
- Phenytoin minor
- Doxycycline Hyclate minor
Tetracycline Also Interacts With
- Theophylline major
- Doxycycline Hyclate moderate
- Minocycline moderate
- Zinc Sulfate minor
- Atovaquone/Proguanil minor
Frequently Asked Questions
What SPL severity band is on file for Doxycycline + Tetracycline?
Compiled FDA labeling labels this pair moderate. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Tetracycline has 12 labeled pairs on file vs Doxycycline's 9. In the moderate band specifically: Doxycycline has 2 (also Rifampin); Tetracycline has 3 (also Doxycycline Hyclate, Minocycline).
What mechanism field is on file for Doxycycline and Tetracycline?
Both of these medicines belong to the same family of antibiotics, which can increase the risk of side effects without helping you get better faster.
Tetracycline carries more major-labeled pairs than Doxycycline
SPL source-record counts only. This page's band is moderate · classes on file: Doxycycline (Tetracycline Antibiotic); Tetracycline (Tetracycline Antibiotic).
Tetracycline has 1 major-labeled pair vs Doxycycline's 0. This page itself is in the moderate band, not the major band.
1 major · 3 moderate · 8 minor · 12 total
- Other moderate peers for Tetracycline
- Doxycycline Hyclate
- Minocycline
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.